Compounds of the general types aryl--SO.sub.2 -alkyl and aryl--SO.sub.2 --C.dbd.C (aryl alkyl sulfones and aryl vinyl sulfones) are useful as intermediates and final products in several areas, dyes being especially prominent. Compounds having this structural unit have generally been prepared by way of multistep sequences starting with thiophenols. Little success has previously been achieved in developing direct, one-step methods for the conversion of aryl compounds to aryl sulfones of the types mentioned above.
It is known that Friedel-Crafts reactions of aryl sulfonyl chlorides provide good yields of diaryl sulfones. See, for example, Friedel-Crafts and Related Reactions, George A. Olah, Ed., Interscience, New York, 1973. However, the corresponding reaction of alkyl sulfonyl chlorides has usually been reported to give very low yields of the desired sulfone. References which indicate the undesirability of this approach to the preparation of the desired sulfones include E. E. Gilbert, J. Org. Chem., 28, 1945 (1963); L. Field and P. H. Settlage, J. Amer. Chem. Soc., 76, 1222 (1953); and C. M. Suter, The Chemistry of Sulfur, John Wiley and Sons, Inc., New York, 1944, pp 673-675.
In an article by W. E. Truce and C. W. Vriesen [J. Amer. Chem. Soc., 75, 5032 (1953)], it is reported that a 70% yield of methyl phenyl sulfone was obtained from methanesulfonyl chloride and benzene using an aluminum trichloride catalyst. However, the reactions of toluene, mesitylene, and halobenzenes with methane sulfonyl chloride in the presence of aluminum trichloride were reported to give only relatively small yields. Likewise, the reaction of p-xylene with methanesulfonyl chloride in the presence of aluminum trichloride has been found by applicants to involve predominantly chlorination of the arene to the virtual exclusion of sulfonylation. Thus, a widely applicable procedure for a direct, one-step conversion of aryl compounds to aryl alkyl sulfones and aryl vinyl sulfones have heretofore not been achieved.
It has now been found, contrary to the expectations of one of ordinary skill in the art, that the desired sulfones can be prepared by the reaction of alkyl and vinyl sulfonyl fluorides with aryl compounds in the presence of aluminum chloride or aluminum bromide catalyst. That is, by replacing alkyl and vinyl sulfonyl chlorides with alkyl and vinyl sulfonyl fluorides, a rapid, convenient, one-step synthesis of aryl alkyl sulfones and aryl vinyl sulfones is achieved. Moreover, the products are provided in yields which are significantly improved over those provided by prior art processes.
The compounds produced by the process of the present invention are useful as intermediates and final products in several areas. For example, certain of the aryl alkyl sulfones are useful as intermediates in the preparation of components for photographic films. The aryl vinyl sulfones are useful as intermediates in the preparation of dyes for wool and polyamide textile products.